Automatic bleeder valve



June 1964 H. A. BRYANT ETAL 3,137,213

AUTOMATIC BLEEDER VALVE Filed April 15, 1963 3 Sheets-Sheet 1 I l I IlNVENTORS HAROLD A. BRYANT BY JOSEPH H.MARCOTT 7 7 ATTOR EY June 1964 H.A. BRYANT ETAL 3,137,213

AUTOMATIC BLEEDER VALVE 3 Sheets-Sheet 2 Filed April 15, 1963 a I, CC

NMT

June 16, 1964 H. A. BRYANT ETAL 3,137,213

AUTOMATIC BLEEDER VALVE Filed April 15, 1965 3 Sheets-Sheet 3 MOTORFIG.5

3,137,213 apron/rant: BLEEnnn vALvr.

United States Patent Harold A. Bryant, North Providence, and Joseph H.Marv cotte, entral Fails, ILL, assignors to Brown & harpe ManufacturingCompany, Providence, R1,, a corporation of Rhode Island Filed Apr. 15,1963, Ser. No. 273,019 Claims. (Cl. 91-420) It has been found thathydraulic operating systems for machine tools, when idled for anyappreciable length of time, tend to pick up a certain amount of airwhich may collect, for example, in the operating cylinder for themovable support with the result that the operation of the support whenfirst placed in operation will tend to be erratic. It is a principalobject of the invention to provide means which will act automaticallywhen the previously idled hydraulic system of the machine is firstbrought up to its full operating pressure, but before said pressure isapplied for the moving of a support, to bleed off any air which may haveaccumulated in the hydraulic system so that a fully dependable andaccurate movement of the machine support from its rest position will beassured when the machine controls are set to call for such movement.

With the above and other objects in view, the several features of theinvention consist in the devices, combinations and arrangement of partshereinafter described and claimed which together with the advantages tobe obtained thereby will be readily understood by one skilled in the artfrom the following description taken in connection with the accompanyingdrawings in which:

FIG. 1 is a view in' front elevation of a grinding machine, a portion ofthe table having been broken away and parts sectioned to illustrateparticularly the table operating hydraulic cylinder;

FIG. 2 is an enlarged view of the table driving cylinder of FIG. 1 shownpartly in section and with the bleeder outlets formed therein;

FIG. 3 is a sectional view in side elevation of the bleeder valveforming part of applicants bleeder valve assembly;

FIG. 4 is a sectional view taken on a line 44 of FIG. 3;

FIG. 5 is a somewhat diagrammatic view of the hydraulic system foroperating the table of the grinding machine shown in FIG. 1 toillustrate the operation of the automatic bleeder valve;

FIG. 6 is a sectional view in side elevation of a mechanicallyinterconnected start-and-stop valve and bleeder valve replacing thecorresponding hydraulically interconnected valves of FIGS. 1 to 5inclusive;

FIG. 7 is an end view of the valve assembly shown in FIG. 6 looking fromthe left; and

FIG. 8 is an end view of the valve assembly shown in FIG. 6 looking fromthe right.

carriage 32. The machine in general may be similar to that described,for example, in prior US. patent to ice Holland et al., No. 2,927,403,dated March 8, 1960, for Hydraulic Operating and Control System for aMachine Tool. Only so much of the machine will be-hereinafter set forthas believed necessary to illustrate the application of the presentinvention thereto. In the embodiment shown, the machine is set up forslicing thin discs from a circular work piece, an extremely thininternal grinding wheel being utilized for this purpose. The internaldisc grinding attachment comprises a casing generally indicated at 44within which is housed an internal grinding disc 46 driven from themachine arbor, not shown, carried by the grinding wheel carriage 42. Acylindrical work piece 48 is shown mounted on a work holder 50 which isin turn rigidly secured to a post 52 on the table 32. In operation thecross slide is advanced so that the work piece projects inwardly throughthe hole in the disc, and the table carrying the work piece is movedtransversely a sufiicient distance to cut off a disc from the workpiece. The table is then backed olf and the operation is repeated. Withthe setup shown it will be appreciated that a very small back-and-forthmovement of the table only is required for making successive cuts in thework piece, each traversing and return movement being followed by aslight advance of the column support 38 which will position the internalgrinding disc for the next succeeding cut.

The hydraulic operating circuit for the table 32 only is here shown in asomewhat diagrammatic form, only so much of the hydraulic system beingshown as believed necessary to show the connection of the inventiontherewith. For a full disclosure of the hydraulic system for operatingthe column support 38 and the table 32, reference may be had to theHolland et al. US. Patent No. 2,927,403, above referred to. Thehydraulic circuit for driving the table 32 as best shown in FIGS. 1 and5 comprises generally a hydraulic cylinder 60 which is mounted on thebase 30 and is provided with a piston 61, and piston rod 62 which isconnected at its outer end to 2. depending lug 64 on the table 32. Oilis supplied from a sump or reservoir 66 by means of a pump 68 driven bya motor 70. From the pump 68 oil flows through a conduit 72 to astart-and-stop valve 74. With the startand-stop valve in the 'onposition shown, oil then flows through a pipe 76 to a reversing valve 78which is connected by conduits 80 and 82 with the two ends of the tableoperating cylinder 60. Assuming the position of the reversing valveshown, oil is returned from the exhaust side of the cylinder 60 throughthe conduit 82 and reversing valve 78, through a return exhaust conduit84 and a relief valve 86 to the reservoir 66. In the event that thepressure produced by the pump 68 in the system exceeds a predeterminedmaximum value, the oil is bypassed from the conduit 72 through a conduit88 and a relief valve 90 directly into the exhaust conduit 84. In theillustration shown, the relief valve 90 is set at p.s.i. When thestart-and-stop valve 74 is shifted from the on to the alternative offposition, oil is bypassed directly from the conduit 72 into an exhaustconduit 92 whence it flows through the bypass conduit 88 and exhaustconduit 84 to the reservoir 66. The relief valve 86 is set at 10 p.s.i.so that a base back pressure is maintained in the system at all timeswhen the motor 70 and pump 68 are in operation.

It is characteristic of hydraulic operating systems of the general typethus far described that when the machine is idled and the hydraulicpressure is shut off for any extended period, there is a tendency forair to leak into the system and to collect particularly along the lengthof the hydraulic cylinder by means of which the machine support isdriven. The hydraulic circuit may normally be purged of any air whichmay have found its way into the operating cylinder by effecting severallong traversing movements of the machine support as, for example, thetable 32 back and forth so that any air which may have collected in thecylinder 60 is driven 011. The improvement hereinafter describedprovides a procedure for eliminating any such air pocket prior to theactual starting of machine operation under conditions such as thoseprovided by the set up shown in FIG. 1 in which the operator cannottraverse the table fully after the machine has been set up for theparticular operation, or where the machine has been idled for any reasonbefore completion of the operation.

In accordance with the invention, a series of bleeder connections areprovided from the cylinder 60 along its length into a bleeder valve 96which is automatically operated when the motor 70 and pump 68 are firstput in operation and before the starting-and-stopping valve 74 isshifted from its stop to its start position to bleed off any air whichmay have accumulated in the system, and particularly in the upperportion of the hydraulic cylinder 60.

The bleeder valve 96 illustrated in detail in FIGS. 3 and 4 comprises arectangular casing 98 having a central bore 100 along its length and endplates 102, 104 which close the ends of the bore. A cylindrical valvemember 106 is supported Within the bore 100 for axial movement thereinbetween bleeding and shut-off positions. A coiled compression spring 108seated within an axial bore in the valve member 106 and at its outer endengaging against the plate 104 acts to bias the valve member 106 to theleft as shown in FIG. 3 to the open or bleeding position. The valvehousing 98 is provided with three bleeder inlet ports 110, 112, 114which extend into the bore 100 from three different sides of the housingin the same transverse plane. A second group of bleeder inlet ports 116,118, 120 is provided through different sides of the casing 98 into thebore 100 in a second transverse plane. The valve is also provided with ahydraulic pressure inlet port 122 through end plate 102 into theleft-hand end of the bore 100 and with an outlet port 124 which isformed in the end plate 104 and connects with the right-hand end of thebore 100. For the open or bleeding position of the valve shown in FIG.3, oil is permitted to pass through the inlet ports 110, 112, 114 past areduced end portion 126 of the valve member 106 into the bore 100 andthence out through the outlet port 124. Oil similarly is permitted topass from the inlet ports 116, 118, 120 into an annular recess 128formed in the periphery of the valve member 106, and thence inwardlythrough a radial drill 130 into the internal bore of the valve member106, and out through the outlet port 124. Movement of the valve member106 to the right against the pressure of spring 108 has the effect ofshutting off all of said inlet ports. The inlet ports 110, 112, 114 ofthe bleeder valve are connected respectively through pipe connections132, 134, 136 with small bleeder ports spaced along the top side of thetable cylinder 60. The bleeder inlet ports 116, 118, 120 are similarlyconnected by means of pipes 138, 140, 142 with inlet ports spaced alongthe top of the cylinder 60. Oil under pressure is supplied to thehydraulic pressure inlet port 122 of the bleeder valve through a pipeconnection 144 from the pressure supply line 72. Oil is exhausted fromthe outlet port 124 through an exhaust pipe connection 146 and a reliefvalve 148 set to provide a back pressure of p.s.i., and thence flowsthrough the lower end of the exhaust line 84 to the reservoir 66.

The operation of the automatic bleeder valve 96 will be described withreference to the somewhat diagrammatic disclosure of the hydraulicoperating system for the machine table 32 as follows:

In the diagram, the machine is shown in running position. It is assumedthat the motor 70 and pump 68 are operating, that the start-and-stopvalve 74 is in its run position, and that the reversing valve 78 is setso that oil at a pressure of 110 p.s.i. is supplied to the left-handface of the piston 62, this pressure being determined by the setting ofthe overflow relief valve 90. Oil is permitted to flow from theright-hand end of the cylinder 60 through the exhaust line 02, 84 to thereservoir against a back pressure of 10 p.s.i. provided by the reliefvalve 86. Under these conditions, oil is supplied at a full operatingpressure of p.s.i. also through the pipe 144 and inlet port 122 to thebleeder valve 96 causing the valve member 106 to be moved to itsright-hand or closed position against the pressure of spring 108 so thatthe bleeder lines 132 to 142 are blocked off.

When the machine is stopped, as by shifting the startand-stop valve 74to the stop position, oil is bypassed from the supply line 72 throughthe start-and-stop valve to the exhaust line 92 and relief valve 86 tothe reservoir 66, thus reducing the pressure on both sides of the piston62 in cylinder 60 to an approximate 10 p.s.i. At the same time thepressure in the supply line 144 to the bleeder valve 96 is reduced to anapproximate 15 p.s.i. which is insufficient to overcome the pressureexerted by the spring 108, so that the bleeder valve is shifted to theon position shown in FIG. 3. Oil under pressure is now permitted toescape through the bleeder lines and the bleeder valve past the reliefvalve 148 which as above noted is set at 5 p.s.i. to the reservoir 66.

If the machine is now completely shut down by stopping motor 70 and pump68, the residual pressure in the system will gradually drop to O. In theevent that the machine is shut down for any length of time, there is aconsiderable probability that air will find its way into the system and,more particularly, into the cylinder 60 where it will collect along theupper inside surface thereof. For this stop condition of the machine,the bleeder valve 96 remains in its open or bleeding position.

When the machine is again started, the motor 70 and pump 68 are firstplaced in operation while the start-andstop valve 74 remains in its stopposition in which oil is bypassed from the supply line '72 through thestartand-stop valve past the relief valve 86 to the reservoir 66.Pressure in all parts of the system will now be controlled by thesetting of the relief valve 86, and will thus approximate 10 p.s.i. Thepressure in the connecting pipe 144 will approximate 15 p.s.i. which isnot enough to move the valve member from its open position against thepressure of spring 108. Each of six bleeder lines 132-142 inclusivewill, therefore, be operative to bleed off oil from the upper portion ofthe cylinder 60 along its length so that any air trapped in the cylinderwill be drawn off, and discharged through the bleeder valve 96 into thereservoir 66. It will take approximately one minute to purge the systemof any entrapped air and no movement of the table is necessary.

When the start-and-stop valve 74 is now shifted to its on position, fulloperating pressure of 110 p.s.i. is directed through the supply line 76to the hydraulic cylinder 60, and through the pipe connection 144 to thebleeder valve causing the valve 106 to be shifted to its off positionagainst the pressure of spring 108 to prevent further bleeding of oilfrom the cylinder.

With the arrangement above described, it will be readily appreciatedthat any air which may have found its way into the system will be drawnoff through the bleeder valve 96 thus insuring a positive and accuratemovement of the piston 62 and table 32 actuated thereby from itspreviously arrested position. The multiplicity of bleeder connectionsprovided insures that air will be exhausted from the top of the cylinder60 along its entire length so that accurate operation of the piston 62from its stop position is assured regardless of where it has stopped orof the direction of travel from said position.

FIGS. 6, 7 and 8 illustrate a modified form of the invention in whichthe bleeder valve is mechanically connected to the start-and-stop valveso that a shifting movement of the start-and-stop valve to the onposition causes the bleeder valve to be shifted to its shut-off posi:

ber 154 having connected to the left-hand end "thereof a stem 156 and amanually operable knob 158. The

left-hand portion of the valve housing 150 and valve member 154constitute a start-and-stop valve asembly which may be identical withthat diagrammatically illus trated in FIG. 5. The right-hand portion ofthe valve housing 150 and valve member 154 constitute a bleeder valveassembly which is similar to that illustrated in FIGS. 3 and 4. Themechanically interconnected startand-stop valve and bleeder valveassemblies contained Within the valve housing 150 of FIG. 6 may befitted bodily into the hydraulic system of FIG. 5 replacing specificallythe start-and-stop valve 74, the bleeder valve 96 andhydraulic pressuresupply pipe 144.

The start-and-stop portion of the combined valve 150 comprises an inletport 160 which is connected with the supply line '72 of FIG. 5, anoutlet port 162 which connects with the pipe 76 leading to the reversingvalve 78 and operating cylinder 60, and a bypass outlet port 164 whichconnects with the bypass pipe line 92. The associated valve member 154is provided with a relatively wide groove 166, which for the offposition of the combined valve shown connects all three of the ports160, 162, 164, and with a groove 168 which for the alternative onposition of the valve connects the supply pipe 160 with the outlet port162 while at the same time the bypass port 164 is shut ofi.

The bleeder valve portion of the combined valve 150 is similar to thebleeder valve illustrated in FIG. 3. Three inlet ports 170, 172, 174 inthe same transverse plane connect respectively with the bleeder pipes132, 134, 136 respectively from the right-hand end of cylinder 60. Threeinlet ports 176, 178, 180 in a second transverse plane connect with thebleeder pipes 138, 140, 142 respectively from the left-hand end ofcylinder 60. The valve member 154 is formed with an annular groove 184which for the off position of the start-and-stop valve shown is alignedwith the three inlet ports 176, 178, 186. A radial passage from thegroove 184 connects with an axial bore 188 in the valve member 154 andwith an exhaust port 190 in end plate 192 through which oil flows intothe exhaust line 146 of FIG. 5. For the machine stop, bleeding positionof the valve member 154 illustrated in FIG. 6, oil is bled from theright-hand end of the operating cylinder 60 through the bleeder pipes132, 134, 136 and inlet ports 170, 172, 174 directly into the centralbore 152 of the valve housing 150 and thence through the outlet port 190to the exhaust line 146. Movement of the manually controlled knob 158and valve member 154 to the on position to the right causes both groupsof inlet ports 170 to 174 and 176 to 130 to be closed off.

The operation of the modified construction illustrated in FIGS. 6, 7 and8 is similar to that previously described in connection with FIGS. 1-5,inclusive, in that for the machine stop position of the start-and-stopvalve control knob 15%, shown in FIG. 6, oil supplied by the pump 68 isbypassed through the bypass connection 92 V causing the pressure in thesystem to be reduced to a minimum value determined by the setting ofrelief valve 86 which may, for example, be in the order of 10 p.s.i. sothat the portions of the operating cylinder 60 at both sides of thepiston 62 will be maintained at the 10 p.s.i. level. Since at the sametime the bleeder valve is moved to the on or open position of FIG. 6 oilwill be bled through each of the bleeder lines 132-142, inclusive,through the bleeder valve to the reservoir 66 against the relativelylower. pressure of relief valve 148 which, as previously noted, is setat 5 p.s.i. Movement of the start-and-stop valve control knob 158 to theright from the position shown in FIG. 6 causes oil at the operatingpressure from pump 68 to be channeled through pipe line 76 to theoperating cylinder 60 while the bypass connection 92 is shut off. At thesame time all of the inlet ports for the bleeder lines 132-142 are shutoil so that no further bleeding of oil from the operating cylinder 60will take place.

The invention having been described what is claimed is:

1. A hydraulic propulsion system for a machine tool support whichcomprises a hydraulic circuit including a hydraulic cylinder connectedto move the support, means for supplying liquid at an operating pressureto said hydraulic circuit, an exhaust connection including a hydraulicresistance through which fluid is exhausted from said circuit against abase back pressure, a start-and-stop' valve in said circuit shiftablebetween on and stop positions, and hydraulic connections in said circuitoperative for the on position of said start-and-stop valve to produce anunbalanced pressure in said cylinder for moving said support, and forthe stop position of said startand-stop valve to produce a balancedpressure in said cylinder to stop said support, bleeder connections fromsaid hydraulic cylinder including a bleeder valve shiftable betweenshut-off and bleeding positions, and means interconnecting the bleedervalve with said start-and-stop valve responsive to the shifting of saidstart-and-stop valve to the on position to shut off the bleeder valveand responsive to the shifting of said start-and-stop valve to the stopposition to open said bleeder valve.

2. A hydraulic propulsion system for a machine tool support whichcomprises a hydraulic circuit including a hydraulic cylinder connectedto move the support, means for supplying liquid at an operating pressureto said hydraulic circuit, an exhaust connection including a hydraulicresistance through which fluid is exhausted from said circuit against abase back pressure, a start-and-stop valve in said circuit shiftablebetween on and stop positions for controlling the flow of said liquidunder pressure to start and stop said tool support, bleeder connectionsfrom said hydraulic cylinder including a bleeder valve shiftable betweenshut-01f and open positions, an exhaust connection from said bleedervalve including a hydraulic resistance having a value below that of saidbase back pressure, and means interconnecting the bleeder valve withsaid start-and-stop valve responsive to the shifting of saidstart-and-stop valve to the on position to shut off the bleeder valveand responsive to the shifting of said start-and-stop valve to the stopposition to open said bleeder valve.

3. A hydraulic propulsion system for a machine tool support whichcomprises a hydraulic circuit including a hydraulic cylinder connectedto move the support, means for supplying liquid at an operating pressureto said hydraulic circuit, an exhaust connection including a hydraulicresistance through which fluid is exhausted from said circuit against abase back pressure, a start-andstop valve in said circuit having a valvemember shiftable between on and stop positions for directing the flow ofsaid liquid under pressure through said circuit to start and to saidexhaust connection to stop said tool support, bleeder connections fromsaid hydraulic cylinder including a bleeder valve having a valve membershiftable between bleeding and shut-ofi positions, an exhaust connectionfrom said bleeder valve including a hydraulic resistance having a valuebelow that of said base back pressure, and means mechanicallyinterconnecting the said bleeder valve member with said startand-stopvalve member for movement as a unit to open said bleeder valve when saidstart-and-stop valve is in the stop position, and to shut ofi' saidbleeder valve when the start-and-stop valve is in the on position.

4. In a hydraulic propulsion system for a machine tool support, thecombination of a hydraulic circuit including a hydraulic propulsioncylinder connected with said support, means for supplying a liquidmedium at an operating pressure to said circuit, an exhaust connectionfrom said circuit including a hydraulic resistance for maintaining abase back pressure in said circuit, bleeder connections from saidhydraulic cylinder including a bleeder valve shiftable between shut-01fand bleeding positions, a start-and-stop valve shiftable to channelliquid at said operating pressure through said circuit and alternativelyto bypass said liquid pressure to said exhaust connection, and controlmeans actuated by said channeled operating liquid pressure to close thebleeder valve and by the reduction of said pressure to said bypass levelto open the bleeder valve.

5. In a hydraulic propulsion system for a machine tool support, thecombination of a hydraulic circuit including a horizontally disposedhydraulic cylinder and piston connected to move said machine toolsupport, said cylinder having connected into the top surface thereof aplurality of bleeder outlets spaced along the length of said cylinder,means for supplying a liquid medium at an operating pressure to saidcircuit, an exhaust connection including a hydraulic resistance throughwhich fluid is exhausted from said circuit against a back pressure, astart-and-stop valve in said circuit shiftable between start-and-stoppositions for controlling the flow of said liquid under pressure tostart and stop said tool support, a bleeder valve connected between saidbleeder outlets and exhaust, including a relief valve between saidbleeder valve and exhaust operable at a pressure less than said backpressure, said bleeder valve being shiftable between bleeding andshut-off positions, and means interconnecting the bleeder valve withsaid startand-stop valve responsive to the shifting of saidstartand-stop valve to the on position to shut olf the bleeder valve,and responsive to the shifting of said start-andstop valve to the stopposition to open said bleeder valve.

No references cited.

1. A HYDRAULIC PROPULSION SYSTEM FOR A MACHINE TOOL SUPPORT WHICHCOMPRISES A HYDRAULIC CIRCUIT INCLUDING A HYDRAULIC CYLINDER CONNECTEDTO MOVE THE SUPPORT, MEANS FOR SUPPLYING LIQUID AT AN OPERATING PRESSURETO SAID HYDRAULIC CIRCUIT, AN EXHAUST CONNECTION INCLUDING A HYDRAULICRESISTANCE THROUGH WHICH FLUID IS EXHAUSTED FROM SAID CIRCUIT AGAINST ABASE BACK PRESSURE, A START-AND-STOP VALVE IN SAID CIRCUIT SHIFTABLEBETWEEN ON AND STOP POSITIONS, AND HYDRAULIC CONNECTIONS IN SAID CIRCUITOPERATIVE FOR THE ON POSITION OF SAID START-AND-STOP VALVE TO PRODUCE ANUNBALANCED PRESSURE IN SAID CYLINDER FOR MOVING SAID SUPPORT, AND FORTHE STOP POSITION OF SAID STARTAND-STOP VALVE TO PRODUCE A BALANCEDPRESSURE IN SAID CYLINDER TO STOP SAID SUPPORT, BLEEDER CONNECTIONS FROM